Football 101: defense

In football, the defense uses certain plays to stop opposing offenses from scoring points. Each play has a formation and scheme designed to stop offensive plays.

Photo Credit: James Boulette

By Wayne Presnell
The goal of the defense in football is to stop opposing offenses from advancing down the field, and scoring points. There are many different philosophies on the best way to accomplish this goal, including which plays are the best.

Each defensive play has a formation and scheme designed to stop a running or passing play. A defensive formation is a predetermined alignment of defensive players on the field. A scheme involves certain movements and coverage of receivers after the offense begins its play.

Defensive plays involve a formation, run stopping scheme, a rushing scheme, and a pass coverage scheme. There are a tremendous number of variations in the schemes, each designed to stop certain types of running or passing plays. Formations are the base of any defense.

The 4-3 defense is a basic defensive formation where the alignment features four defensive lineman and three linebackers in the front seven, thus the name 4-3. There are two defensive ends, one on each end of the line, and two defensive tackles in between. Behind the defensive line are three linebackers. Two cornerbacks, one on each side of the field, line up to cover the wide receivers. There are also two safeties. The exact position of the defensive backs (cornerbacks and safeties) depends on the type of pass coverage. Pass coverage is man to man, where defensive players cover receivers by themselves, zone coverage, where defensive players cover an area of the field or zone, or a combination of both.

Additional wording of a play describes the type of pass coverage and defensive line movements. For example, a 4-3 maximum blitz, indicates the initial 4-3 formation and the defensive lineman, linebackers and even one of the safeties will rush the passer ignoring the run, trying to sack the quarterback before he can throw the ball. There are only three people left to cover the receivers man to man.

The Over/Under 4-3 defense is a variation of the basic 4-3 defense that allows the defense to shift more linemen to the suspected point of attack. In the over formation, three lineman shift to the offense's strong side (side with the TE) and in the under formation, three lineman shift to the offense's weak side. These are used primarily to stop the run. Pass coverage will vary with this formation.

The 6-1 defense is a variation of the 4-3 formation. The alignment features four down lineman and three linebackers in the front seven, but two linebackers move up on the defensive line, putting six defenders on the line. This formation is used to stop the run or pass.

The 3-4 defense is a defensive formation which uses the alignment of three defensive lineman and four linebackers in the front seven. The 3-4 Eagle defense uses the same alignment, but a linebacker is inserted in the middle of two defensive lineman, leaving the formation with two linemen and five linebackers. The 3-4 is primarily used to stop the pass but can be used to stop the run.

The 4-4 defense is a defensive formation in which the alignment features four down lineman and four linebackers. The 5-2 alignment features five down lineman and two linebackers in the front seven. These formations are designed to stop the run.

The nickel defense is a defensive formation designed to stop the pass. The alignment features four down lineman, two linebackers, and five defensive backs. The extra defensive back is used in pass coverage.

The dime defense is a defensive formation also designed to stop the pass. The alignment features either four down lineman, one linebacker, and six defensive backs or three down lineman, two linebackers, and six defensive backs. Again, the extra defensive backs are used in pass coverage.